In blood dialysis wounds are caused by puncturing an artery or vein by a cannula or an arteriovenous (AV) fistula or graft by a cannula or fistula catheter to remove blood for dialysis. The purified blood is returned to the patient by venous infusion through a second cannula or fistula catheter. A cannula or fistula catheter of this kind is usually secured to the patient's skin by adhesive tape. During dialysis the cannula or fistula catheter may be accidentally withdrawn. This results in immediate bleeding which, if is not noticed and stopped at once, may lead to the loss of a large volume of blood. Also other wounds that have been closed by surgery or by mere coagulation may start to bleed again, for instance during sleep, and thereby put the patient at risk if the bleeding is not noticed and stopped with in a short time.
An apparatus for detection of blood leakage from wounds is disclosed in WO 2006/001759 A1. The known apparatus comprises a single use disposable blood leakage detection device comprising a patch, a means for temporary fixation of the patch at a wound, an optical fibre for conducting light from electronic emission means to electronic detection means of the apparatus, the fibre at its passage via the patch comprising a zone in which the reflectance of the fibre wall in respect of the light conducted by the fibre is affected by blood conducting the wall in the zone, a difference in returned light indicating a leakage of blood from the wound. At its free ends the fibre comprises connectors to put it in radiative communication with the emission and detection means.